How do I setup the end user notifications?

New Contributor III

Here is the github link to what I am referring to:

I do not understand how to set this app up. I am not sure which file to modify to configure a notification for lets say a macOSX upgrade. I assume after I configure the notification in I assume I package it and add it to the policy I am deploying the Mac OSX upgrade with, or two separate ones that daisy chain together. I plan on using this notification for all software distribution and macOSX upgrades.